Organisms of the genus Mycobacteria are responsible for infection of a variety of animals, including man. An important difference between Mycobacteria and other bacteria is that the former have a thick, lipid-rich envelope. This envelope gives the cells their distinctive characteristics, which include: hydrophobicity, resistance to chemical injury by acids, alkalis and many of the disinfectants used to kill other bacteria, resistance to attack by macrophages in which Mycobacteria are then able to multiply to cause disease, ability to survive long periods of starvation or aridity without dehydration and allergic and immunogenic properties.
The envelope thus provides a means to identify and classify the numerous species of Mycobacteria. Traditionally, there have been two primary diagnostic methods applicable to the detection of Mycobacteria. These are: (i) the direct observation of the etiological agent (e.g., by microscopic techniques) and (ii) its culture.
Direct observation is generally reliable for some Mycobacterial species, but requires expensive equipment and highly trained personnel. Culturing of Mycobacteria, although reliable, is time consuming and inconvenient. Depending on the species, specimens must be incubated from 2-8 weeks before visible colonies appear. A need exists for an improved method for the detection of Mycobacteria.